Construction & quality
CEE483 – Fall 2020
1
CEE 483 Fall 2020 Highway Materials, Construction Dr.
Kaloush & Quality
Homework Assignment #4 Date Assigned: 9/28/20
Date Due: 10/2/20
1. The results of a compaction test on samples of soil that are to be used for a highway
construction project are listed below.
Trial Bulk Density (lb/ft3) Water Content (%)
1 122.8 6.8
2 131.6 9.1
3 135.9 11.0
4 137.3 12.8
5 136.2 15.0
6 133.6 16.6
a. Plot the compaction curve and determine the max dry density of compaction for
this soil at the optimum water content.
b. Draw the zero air voids curve on the plot (make any necessary assumption for the
calculations).
c. What are the advantages of plotting / knowing the zero air voids curve.
2. Briefly explains the use of Sheeps / Tamping foot compactor, including: its use (when
and for what type of materials), lift construction action, thickness limitations, and the
needed follow up process.
3. A highway construction project specifies 96% compaction. Lab tests on the soil being
used indicated that it has a maximum dry density of 116.8 lb/ft3 at an optimum water
content of 12.3%. Field tests give the dry density is 110.0 lb/ft3 at 15.6% water
content. Were the specifications met? Explain.
4. A subgrade soil with a CBR of 8. Estimate the Resistance Value, Resilient Modulus,
and the Dynamic Cone Penetrometer Index.
5. Develop a tabular relationships between CBR, R-Value, Mr and DCP for a range of
CBR: 3, 5, 8, 10, 15, 20, and 30. Plot the relationships and comment on the trends.
76
OVERVIEW
America’s roads are often crowded, frequently in poor condition, chronically underfunded, and are
becoming more dangerous. More than two out of every five miles of America’s urban interstates are
congested and traffic delays cost the country $160 billion in wasted time and fuel in 2014. One out of
every five miles of highway pavement is in poor condition and our roads have a significant and
increasing backlog of rehabilitation needs. After years of decline, traffic fatalities increased by 7% from
2014 to 2015, with 35,092 people dying on America’s roads.
CAPACITY & CONDITION
With over four million miles of roads crisscrossing the United States, from 15 lane interstates to
residential streets, roads are among the most visible and familiar forms of infrastructure. In 2016 alone,
U.S. roads carried people and goods over 3.2 trillion miles—or more than 300 round trips between Earth
and Pluto. After a slight dip during the 2008 recession, Americans are driving more and vehicle miles
travelled hit a record high in 2016.
With more traffic on the roads, it is no surprise that America’s congestion problem is getting worse, but
adding additional lanes or new roads to the highway system will not solve congestion on its own. More
than two out of every five miles of the nation’s urban interstates are congested. Of the country’s 100
largest metro areas, all but five saw increased traffic congestion from 2013 to 2014. In 2014, Americans
spent 6.9 billion hours delayed in traffic—42 hours per driver. All of that sitting in traffic wasted 3.1
billion gallons of fuel. The lost time and wasted fuel add up—the total in 2014 was $160 billion.
77
According to TRIP, 21% of the nation’s highways had poor pavement condition in 2015. Driving on roads
in need of repair cost U.S. motorists $120.5 billion in extra vehicle repairs and operating costs in 2015, or
$533 per driver.
In some areas, state and local governments have reconsidered road materials, converting some low-
traffic, rural roads from asphalt to gravel. These roads were mostly paved when asphalt and
construction prices were low, but with construction costs rising faster than infrastructure funding,
converting the roads back to gravel is a more sustainable solution for maintenance. At least 27 states
have de-paved roads, primarily in the last five years.
FUNDING & FUTURE NEED
The U.S. has been underfunding its highway system for years, resulting in a $836 billion backlog of
highway and bridge capital needs. The bulk of the backlog ($420 billion) is in repairing existing highways,
while $123 billion is needed for bridge repair, $167 billion for system expansion, and $126 for system
enhancement (which includes safety enhancements, operational improvements, and environmental
projects). The Federal Highway Administration estimates that each dollar spent on road, highway, and
bridge improvements returns $5.20 in the form of lower vehicle maintenance costs, decreased delays,
reduced fuel consumption, improved safety, lower road and bridge maintenance costs, and reduced
emissions as a result of improved traffic flow.
78
The federal government is a major source of funding for the construction of highways through the
federal Highway Trust Fund and competitive grant programs for specific projects, like TIGER. In 2014, the
federal government spent $43.5 billion on capital costs for highway infrastructure (including bridges)
and state and local governments spent $48.3 billion. State and local governments are responsible for the
operation and maintenance (O&M) of highways (with the exception of roads on federal lands). They
spent $70 billion on O&M in 2014, while the federal government spent $2.7 billion.
Federal investment in highways has historically been paid for from a dedicated, user fee-funded source,
the Highway Trust Fund. However, the Trust Fund has been teetering on the precipice of insolvency for
nine years due to the limitations of its primary funding source, the federal motor fuels tax. The tax of
18.4 cents per gallon for gasoline and 24.4 cents for diesel has not been raised since 1993, and inflation
has cut its purchasing power by 40%. Between 2013 and 2017, 17 states and the District of Columbia
raised their motor fuels taxes. A number of states are exploring other revenue sources for funding road
investment, including mileage-based user fees. With continued improvements in vehicle fuel efficiency
and the popularity of hybrid and electric vehicles, mileage-based user fees present a promising long-
term funding alternative to the motor fuels tax.
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PUBLIC SAFETY
35,092 people were killed in motor vehicle crashes in 2015. Traffic fatalities decreased significantly over
the last decade, but abruptly increased by 7% from 2014 to 2015 and preliminary data shows fatalities
rose 8% in the first nine months of 2016. 9.5% more pedestrians and 12.2% more bicyclists were killed
by crashes in 2015 than 2014, emphasizing the importance of designing streets for the safety of all
users.
The recent increase in fatal
crashes is not yet fully
understood, but communities
are trying to save lives through
improvements in road design,
such as widening lanes and
shoulders; adding and
improving medians, guard
rails, and parallel rumble
strips; upgrading road
markings and traffic signals;
and using new materials, such
as high friction surface
treatments. Another
increasingly popular method
communities are using to
improve the safety of their
roads for all users is the “road
diet,” which reconfigures a road, reducing the number of lanes and adding safety features. For instance,
a four-lane, undivided highway could be converted to a two-lane highway with a center two-way left-
turn lane. The extra space created by removing a lane can be reallocated for other safety-oriented uses
such as bike lanes, pedestrian refuge islands, or designated transit stops. The Federal Highway
Administration’s Highway Safety Improvement Program (HSIP) collects data, performs research, and
provides funding to states to implement these infrastructure-based safety measures.
INNOVATION AND RESILIENCE
New road design, construction, maintenance, and management technologies and techniques are
constantly being developed. The Federal Highway Administration’s Every Day Counts program has
played an important role in collecting and evaluating new ideas and promoting the deployment of
proven, market-ready strategies. These innovations have included the use of 3D engineered models for
more accurate and efficient planning and construction; new methods to determine when, where and
how to best preserve pavement; and tools to make permitting reviews faster and more efficient. New
materials and technology are also helping roads become more sustainable and resilient, such as greater
use of permeable paving materials to reduce storm runoff, as well as the use of recycled materials in
pavement.
80
RECOMMENDATIONS TO RAISE THE GRADE
• Increase funding from all levels of government and the private sector to tackle the massive
backlog of highway needs.
• Fix the federal Highway Trust Fund by raising the federal motor fuels tax. To ensure long-term,
sustainable funding for the federal surface transportation program, the current user fee of 18.4
cents per gallon on gasoline and 24.4 cents per gallon on diesel should be raised and tied to
inflation to restore its purchasing power, fill the funding deficit, and ensure reliable funding for
the future.
• Tackle congestion through policies and technologies that maximize the capacity of the existing
road network and create an integrated, multimodal transportation system.
• Prioritize maintenance and the state of good repair to maximize the lifespan of roads.
• State and local governments should ensure their funding mechanisms (motor fuel taxes or
other) are sufficient to fund their needed investment.
• All levels of government need to think long-term about how to fund their roads and consider
potential alternatives to the motor fuel taxes, including further study and piloting of mileage-
based user fees.
• Increase investment and expand the federal Highway Safety Improvement Program to find new
ways and further propagate existing methods to make roads safe for all users.
DEFINITIONS
Vehicle miles travelled – the total mileage travelled nationally by all vehicles over one year
SOURCES
Congressional Budget Office. Public Spending on Transportation and Water Infrastructure, 1956 to 2014. March 2,
2015.
Texas Transportation Institute. 2015 Urban Mobility Scorecard. August 2015.
Fay, Laura; Kroon, Ashley; Skorseth, Ken; Reid, Richard; and David Jones. Converting Paved Roads to Unpaved.
2016.
TRIP, The Interstate Highway System turns 60: Challenges to Its Ability to Continue to Save Lives, Time and Money.
June 27, 2016.
TRIP, National Fact Sheet. August 2016.
U.S. Department of Transportation, 2015 Status of the Nation’s Highways, Bridges and Transit: Conditions and
Performance. January 2017.
U.S. Department of Transportation, Federal Highway Administration. Highway Statistics 2014: Chart VMT-422C.
March 21, 2016.
Slide
1
HMA Mix Type Selection
1
Three basic mixture types are
discussed, each have their own
benefits and structural or functional
usage
Slide 2
2
DENSE-GRADED
Most common type
Do you know what the gradation chart
look like for this mixture?
There are different size aggregates
(wide range) represented in the mix.
Asphalt contents are in the range of 4.5
to 6 percent
Air voids are typically 5 to 7 percent
Slide 3
3GAP-GRADED
Got popular in recent decades.
Do you know what the gradation chart
look like for this mixture?
There is a gap in the gradation, that is
some large aggregates and some finer
ones, mid-size range is mostly missing
.
What are the benefits? Structurally is
good and allows for higher addition of
binder especially when modified. Can
provide some permeability as well
Asphalt contents are in the range of 6
to 7 or 8 percent (the higher percentage
when
polymer or rubber modified)
Air voids are typically in the 7 percent
range, have seen values with 9 percent.
More permeable but you want to stay
at the 7-8 percent range for best
performance
Slide 4
4
OPEN-GRADED
Got popular and widely used as a
surface mixture course.
Do you know what the gradation chart
look like for this mixture?
The gradation of the aggregates are
pretty much in a very narrow band
with similar sizes, very little fines.
What are the benefits? Does it provide
structural support? How about the
functional benefits? It also allows for
higher binder content and can provide
some great permeability and therefore
reduce the standing water on the
surface.
Typically used with modified binders
such as polymers and rubbter. Asphalt
contents are in the range of 8 to 9.5
percent (the higher percentage when
polymer or rubber modified)
Air voids are typically in the 18 to 20
percent range.
Slide 5
Highway Noise
5
Slide 6
Highway Safety
• Increase highway safety measures by increasing driver visibility, reducing
standing surface water, and improving skid resistance.
6
Slide 7
7
Slide 8
8
Slide 9
9
Slide 10
10
Slide 11
11
Slide 12
HMA MATERIALS
12
Slide 13
Backgroun
d
• First US hot mix asphalt (HMA)
constructed in 1870’s
– Pennsylvania Ave.
– Used naturally occurring asphalt
from surface of lake on Island of
Trinidad
• Two sources
– Island of Trinidad
– Bermudez, Venezuela
Slide 14
14
Slide 15
15
Slide 16
Petroleum-Based Asphalts
• Asphalt is waste product from refinery processing of
crude oil
– Sometimes called the “bottom of the barrel”
• Properties depend on:
– Refinery operations
– crude source
16
Gasoline
Kerosene
Lt. Gas Oil
Diesel
Motor Oils
Asphalt
Barrel of Crude Oil
Slide 17 Asphalt Cement Components
• Asphaltenes
– Large, discrete solid inclusions (black
)
– High viscosity component
• Resins
– Semi-solid or solid at room temperature
• Fluid when heated
• Brittle when cold
• Oils
– Colorless liquid
– Soluble in most solvents
– Allows asphalt to flow
17
Slide 18 Refinery Operation
18
FIELD
STORAGE
PUMPING
STATION
LIGHT DISTILLATE
HEAVY DISTILLATE
PROCESS
UNIT
ASPHALT
CEMENTS
FOR PROCESSING INTO
EMULSIFIED AND
CUTBACK ASPHALTS
STIL
L
AIR
AIR
BLOWN
ASPHALT
STORAGE
TOWER
DISTILLATION
REFINERY
RESIDUUM
OR
GAS
PETROLEUM
SAND AND WATER
CONDENSERS
AND
COOLERS
TUBE
HEATER
MEDIUM DISTILLATE
Slide 19
Types
• Asphalt cements
• Cutbacks
• Emulsions
19
.
Slide 20
Early Specifications
• Lake Asphalts
– Appearance
– Solubility in carbon disulfide
• Petroleum asphalts (early 1900’s)
– Consistency
• Chewing
• Penetration machine
– Measure consistency
Slide 21
Binder Tests
• Conventional Tests
2
1
Superpave /
SHRP Tests
Penetration AASHTO T49-93
Softening Point AASHTO T53-
92
Rotational Viscosity AASHTO TP
48
Dynamic Shear
Rheometer (DSR):
AASHTO PP1
Bending Beam
Rheometer
(BBR): AASHTO TP1-98
Slide 22 Penetration Testing
• Sewing machine needle
• Specified load, time, temperature
100 g
Initial
Penetration in 0.1 mm
After 5 seconds
The penetration test started out using a
No. 2 sewing machine needle mounted
on a shaft for a total mass of 100 g.
This needle was allowed to sink into
(penetrate) a container of asphalt
cement at room temperature (25 oC)
for 5 seconds. The consistency
(stiffness) of a given asphalt was
reported as the depth in tenths of a
millimeter (dmm) that the needle
penetrated the asphalt.
Slide 23
Penetration Grades
40-50, 60-70, 85-
10
0
120-150, 200-
300
# – #
Maximum penetration
Minimum penetration
23
Slide 24
Viscosity Graded Specifications
24
Slide 25
AC Grades
AC-2.5, AC-5, AC-
10
AC-20, AC-30, AC-
40
AC- # 1/100 of midpoint of the
allowable viscosity range.
AC-20, viscosity range
1,600 to 2,400 poises.
Asphalt cement
25
Slide 26
AR Grades
AR-10, AR-20, AR-40
AR-80, AR-1
60
AR- # 1/100 of midpoint of
viscosity after aging.
AR-40, viscosity range
3,000 to 5,000 poises.
Aged residue
26
Slide 27
RTFO
27
Slide 28
Flash Point
• Safety test
• Minimum temperature
with sufficient vapors to
“flash” when exposed to
flame
Slide 29
Solubility (Purity)
29
A sample of asphalt binder is dissolved
in a solvent then filtered through a
Gooch crucible mounted in the top of a
vacuum flask. The amount of
insoluble material retained on the filter
represents the impurities in the asphalt
binder.
Slide 30
Testing
Absolute viscosity
– U-shaped tube with timing marks &
filled with
asphalt
– Placed in 60C bath
– Vacuum used to pull asphalt through
tube
– Time to pass marks
– Viscosity in Pa s (Poise)
At the 60 oC test temperature, the tube
is charged at 135 oC and then placed in
the test temperature bath. The tube
temperature is allowed to equalize
with the bath temperature, a vacuum
line is attached to the top of the small
diameter tube, and the flow is started.
The time it takes the asphalt to flow
past the timing marks times the tube
calibration constant gives the viscosity
of the asphalt in Poise.
Slide 31
Rotational Viscometer
Measures viscosity
• Ability to pump binder at
asphalt plant
• Establish temperature
versus viscosity
relationship
Slide 32
Rotational Viscometer
spindle
torque
sample
sample
chamber
32
Slide 33
Temperature Susceptibility
Viscosity
33
Temperature
Too brittle (Thermal cracking)
Too soft (Rutting)
Optimum
range
Of viscosity
Slide 34
Viscosity-Temperature Relationship
34
Viscosity – Temperature Relationship (Original Binder)
ARAC PG 58-28: y = -2.4795x + 7.6903
R
2
= 0.989
0.0
0
.2
0.4
0.6
0.8
1.0
1.2
1.4
2.70 2.75 2.80 2.85 2.90 2.9
5
Log (Temp,
o
Rankine)
L
o
g
(
L
o
g
v
is
c
o
si
t
y
,
cP
)
(41) (103) (171) (248) (335) (432)(deg F)
Pen
59, 77oF
Soft. Point
139oF
Brookfield Viscosity
200-350oF
Slide 35
Mixing/Compaction Temps
35
.1
.2
.3
.5
1
10
5
100 110 120 130 140 150 160 170 180 190 200
Temperature,
C
Viscosity, Pa s
Compaction Range
Mixing Range
To establish mixing and compaction
temperatures it is necessary to develop
a temperature viscosity chart. This can
be done by determining the viscosity at
two different temperatures – generally
135 C and 165 C. These two
viscosities are then plotted on the
graph above and a straight line is
drawn between the two points.
The desired viscosity range for mixing
is between 0.15 and 0.19 Pa-s and
0.25 and 0.31 Pa-s for compaction.
Appropriate mixing and compaction
temperatures are selected as the
temperature where these viscosity
requirements are met. This
information can be obtained from the
suppliers. In many DOTs this
information is developed during the
mix design process.
If using modified binders – it is
recommended that you should contact
the supplier to determine the mixing
and compaction temperatures.
Slide 36
40
50
60
70
85
100
120
150
200
300
Penetration Grades
AC 40
AC 20
AC 10
AC 5
AC 2.5
100
50
10
5
V
is
c
o
s
it
y
,
6
0
C
(
1
4
0
F
)
AR 16000
AR 8000
AR 4000
AR 2000
AR 1000
General Comparison
This figure provides a general
comparison of the various traditional
specifications. While there is no direct
relationship between the
specifications, there is a general
relationship between stiffness and
viscosity. Higher penetration numbers
correspond with lower viscosities.
Slide 37
New Superpave Binder Specifications
Intended to improve pavement performance by
reducing the potential to:
Permanent deformation
Fatigue cracking
Low-temperature cracking
Excessive aging from volatilization
Pumping and handling
37
Slide 38
Test Equipment Performance Property
Rotational
Viscometer
Dynamic
Shear
Rheometer
Bending Beam
Rheometer
Direct
Tension
Tester
Handling
Pumping
Permanent
Deformation
Fatigue
Cracking
Thermal
Cracking
Flow
Rutting
Structural
Cracking
Low Temp.
Cracking
Slide 39
Dynamic Shear Rheometer
–Tests complex shear
modulus of binders
–measures the resistance
to shear deformation in
the linear visco-elastic
range
Chapter 9: Asphalt
height (h)
radius (r)
torque (T)
deflection angle (Q)
Slide 40 Dynamic Shear Rheometer
Applied Stress
Fixed
Plate
Asphalt
Oscillating
Plate
B C
A
Position of
Oscillating Plate
A
B
A
C
A
Time
1
cycle
40
Slide 41
41
Elastic Viscous
Time
A
A
B
C
Strain
Strain in-phase
d = 0o
Strain out-of-phase
d = 90o
If a material is elastic, then the strain
response will be in-phase with the
applied stress. If a material is viscous,
then the response will be 90o out of
phase.
Slide 42
42
Viscous Modulus, G”
Storage Modulus, G’
Complex Modulus, G*
d
Complex Modulus is the vector sum of the
storage and viscous modulus
When a material has both an elastic
and viscous component to its behavior,
this type of testing can sort out the
contribution of each to the total
response. Delta is the phase angle, that
is, the degrees that the strain response
is out of phase with the applied stress.
The complex modulus, G*, is the
vector sum (Pythagorean’s theorem).
If delta is 0, the G* equals the storage
modulus. In other words, the response
is all elastic. If delta is 90o, then the
response is all viscous (G* = viscous
component).
Slide 43
Bending Beam Rheometer
–Tests low temperature stiffness properties of binders
– Measures midpoint deflection of a simply supported
beam
Slide 44
Bending Beam Rheometer
• S(t) = P L3
44
4 b h3 d (t)
Where:
S(t) = creep stiffness (M Pa) at time, t
P = applied constant load, N
L = distance between beam supports (102 mm)
b = beam width, 12.5 mm
h = beam thickness, 6.25 mm
d(t) = deflection (mm) at time, t
The equation used to determine the
change in stiffness with time is that for
a simply supported beam. The
geometry parameters remain constant
throughout the test. The only values
that change are the deformation of the
beam due to the static load and the
stiffness calculated using this time-
dependent deformation.
Slide 45
Direct Tension
• thermal
cracking
properties
FHWA
Slide 46 Direct Tension Tester
L
Load
L+ L
L
failure strain (f ) =
effective length (L )
change in length ( L)
eL
e
46
f
stress
strain
f
Slide 47 Summary
47
Fatigue
CrackingRutting
RTFO
Short Term AgingNo
aging
Construction
[RV]
[DSR]
Low Temp
Cracking
[BBR]
[DTT]
PAV
Long Term Aging
This figure summarizes the testing
required for the PG asphalt binder
specification.
Slide 48
48
PAV Components
Bottom of
pressure
aging
vessel
Rack of individual
pans
(50g of asphalt /
pan)
Vessel Lid Components
This photograph provides an example
of an older type of pressure aging
vessel equipment. This old version is
shown because it clearly shows all of
the key elements in all PAV units (old
or new). There are currently several
makes and models of PAV ovens
available.
Slide 49
PG 46 PG 52 PG 58 PG 64 PG 70 PG 76 PG 82
(Rotational Viscosity) RV
90 90 100 100 100 (110) 100 (110) 110 (110)
(Flash Point) FP
46 52 58 64 70 76 82
46 52 58 64 70 76 82
(ROLLING THIN FILM OVEN) (ROLLING THIN FILM OVEN) RTFO RTFO Mass Loss Mass Loss << 1.00 % 1.00 %
(Direct Tension) DT
(Bending Beam Rheometer) BBR Physical Hardening
28
-34 -40 -46 -10 -16 -22 -28 -34 -40 -46 -16 -22 -28 -34 -40 -10 -16 -22 -28 -34 -40 -10 -16 -22 -28 -34 -40 -10 -16 -22 -28 -34 -10 -16 -22 -28 -34
Avg 7-day Max, oC
1-day Min, oC
(PRESSURE AGING VESSEL) (PRESSURE AGING VESSEL) PAVPAV
ORIGINALORIGINAL
< 5000 kPa
> 2.20 kPa
S < 300 MPa m > 0.300
Report Value
> 1.00 %
20 Hours, 2.07 MPa
10 7 4 25 22 19 16 13 10 7 25 22 19 16 13 31 28 25 22 19 16 34 31 28 25 22 19 37 34 31 28 25 40 37 34 31
(Dynamic Shear Rheometer) DSR G* sin d
( Bending Beam Rheometer) BBR “S” Stiffness & “m”- value
-24 -30 -36 0 -6 -12 -18 -24 -30 -36 -6 -12 -18 -24 -30 0 -6 -12 -18 -24 -30 0 -6 -12 -18 -24 -30 0 -6 -12 -18 -24 0 -6 -12 -18 -24
-24 -30 -36 0 -6 -12 -18 -24 -30 -36 -6 -12 -18 -24 -30 0 -6 -12 -18 -24 -30 0 -6 -12 -18 -24 -30 0 -6 -12 -18 -24 0 -6 -12 -18 -24
(Dynamic Shear Rheometer) DSR G*/sin d
(Dynamic Shear Rheometer) DSR G*/sin d
< 3 Pa.s @ 135 oC
> 230 oC
CEC RWM
58
64
Test Temperature
Changes
Spec Requirement
Remains Constant
> 1.00 kPa
49
Slide 50
Superpave Asphalt Binders
• Grading System and Selection Based Primarily on Climate
50
PG 58-22
Performance
Grade
Average 7-day
max pavement
design temp
Min pavement
design temp
Slide 51
6 degree increments
Slide 52
Aggregates
52
Slide 53
Excavation
53
* Natural sands and gravels
– Underwater sources
+ Rivers & lakes
Barge-mounted dredges, draglines,
scoop, conveyors, or pumps
+ Relatively clean
– Land sources
+ Gravel or sand pits
Bucket loader
Slide 54
Sizing
54
Stockpiling
Slide 55
Aggregate Properties
• Shape and texture
•
Soundness
•
Toughness
• Absorption
• Specific gravity
• Strength and modulus
• Gradation
• Deleterious materials and
cleanness
• Alkaline reactivity
• Affinity for asphalt
Slide 56
Chapter 5: Aggregates
angular rounded flaky
elongated flaky & elongated
Slide 57
Coarse Aggregates Particle Shape & Surface Texture
Evaluation
• Texture and angularity –
Fractured faces
visual inspection to determine the percent of
aggregates with:
• no fractured faces
• % one fractured face
• % more than one fractured face
Slide 58
Common Aggregate Properties
Toughness
Soundness
Deleterious Materials
Gradation
58
Source aggregate properties are those
properties which are measured for the
aggregate as-stockpiled and are
commonly used for aggregate source
acceptance control. These properties
are toughness, soundness, and
deleterious materials. In addition, the
gradations of individual stockpiles
may be evaluated.
Slide 59 LA Abrasion Test
59
– Approx. 10% loss for extremely hard igneous rocks
– Approx. 60% loss for soft limestones and sandstones
Rotate for 500 revolutions at 30 to 33 rpm’s
This photo shows the equipment
needed for the Los Angeles abrasion
test. The panel on the side of the drum
is removed and the aggregate and steel
balls are placed inside. The panel is
replaced and the drum rotated the
prescribed number of cycles.
Examples of typical values are noted at
the bottom of this photo.
Slide 60
60
Soundness
* Estimates resistance to weathering .
* Simulates freeze/thaw action by successively wetting
and drying aggregate in sodium sulfate or magnesium
sulfate solution
+ One immersion and drying is considered one
cycle
* Result is total percent loss over various sieve intervals
for a prescribed number of cycles
+ Max. loss values typically range from
10 to 20%per 5 cycles
Weathering of aggregates is simulated
by repeated immersion in saturated
solutions of either sodium or
magnesium sulfate followed by oven
drying. The internal expansive force
from the expansion of the rehydration
of the soluble salts upon re-immersion
simulates freeze-thaw damage. The
difference between the original and
final mass, expressed as a percent of
the original mass is the percent loss. A
weighted percentage is used when
several fractions are tested. The
soundness of both fine (passing the
4.75 mm sieve) and coarse aggregate
can be determined using this test.
Slide 61
Soundness
61
Before After
Damage to the aggregate after a
number of wet-dry cycles can be seen
by visual examination as well as in the
change in gradation.
Slide 62
Chapter 5: Aggregates
Slide 63
63
Clay Lumps and Friable Particles
ASTM C 142
Dries a given mass of agg., then soaks for 24
hr., and each particle is rubbed. A washed
sieve is then performed over several screens,
the aggregate dried, and the percent loss is
reported as the % clay or friable particles.
Deleterious material is the mass
percent of contaminants such as clay
lumps, shale, wood, mica, and coal in
the blended aggregate. This test can
also be performed for both fine and
coarse aggregates. The mass
percentage of the material lost during a
wet sieve is reported as the percent of
clay lumps and friable particles.
Slide 64
Gradations
64
• Aggregate Gradation
– The distribution of particle sizes expressed as
a percent of total weight.
– Determined by sieve analysis
Slide 65
65
Gradations – Computation
Sieve Mass Cumulative
Retained Mass Retained % Retained % Passing
9.5
4.75
2.36
1.18
0.60
0.30
0.15
0.075
Pan
0.0
6.5
127.4
103.4
72.8
6
4.2
60.0
83.0
22.4
0.0
6.5
133.9
237.3
310.1
374.3
434.3
517.3
539.7
0.0
1.2
24.8
44.0
57.5
69.4
80.5
95.8
100.0
100.0
98.9
75.2
56.0
42.6
30.6
19.5
4.2
0.0
This is an example of the calculations
necessary for a sieve analysis. What is
not shown is that the 22.4 g of material
in the pan is the sum of the mass which
was washed past the0.075 mm sieve in
the first part and the mass of the
aggregate retained in the pan after the
mechanical sieve analysis. This is an
important point as the final gradation
reported needs to reflect the true
percentage of fractions in the stockpile
which will be used during
construction.
Slide 66
Aggregate Size Definitions
• Nominal Maximum Aggregate Size
–one size larger than the first sieve to retain
more than 10%
• Maximum Aggregate Size
–one size larger than nominal maximum size
66
100
100
90
72
65
48
36
22
15
9
4
100
99
89
72
65
48
36
22
15
9
4
For HMA pavements these are the
definitions for gradations.
Slide 67
Chapter 5: Aggregates
Slide 68
Chapter 5: Aggregates
Types of Gradation
Slide 69
Hot Mix Asphalt Concrete (HMA)
Mix Designs
• Objective:
– Develop an economical blend of aggregates and asphalt that
meet design requirements
• Historical mix design methods
– Marshall
–
Hveem
• New
– Superpave gyratory
69
Slide 70
Requirements in Common
• Sufficient asphalt to ensure a durable pavement
• Sufficient stability under traffic loads
• Sufficient air voids
– Upper limit to prevent excessive environmental damage
– Lower limit to allow room for initial densification due to traffic
• Sufficient workability
70
Slide 71
HMA Volumetric Terms
• Bulk specific gravity (BSG) of compacted HMA
• Maximum specific gravity
• Air voids
• Effective specific gravity of
aggregate
• Voids in mineral aggregate,
VMA
• Voids filled with asphalt,
VFA
Slide 72
BSG of Compacted HMA
• AC mixed with agg. and compacted into sample
Mass agg. and AC
Vol. agg., AC, air voids
Gmb
=
Slide 73
Maximum Specific Gravity
Loose (uncompacted) mixture
Mass agg. and AC
Vol. agg. and AC
Gmm =
Slide 74
Percent Air Voids
Calculated using both specific gravities
Gmb
Gmm
Air voids = ( 1 – ) 100
Mass agg + AC
Vol. agg, AC, Air Voids
Mass agg + AC
Vol. agg, AC
=
Vol. agg, AC
Vol. agg, AC, Air Voids
Slide 75
Effective volume = volume of solid aggregate particle +
volume of surface voids
not filled with asphalt
Gse =
Mass, dry
Effective Specific Gravity
Effective Volume
Absorbed asphalt
Vol. of water-perm. voids
not filled with asphalt
Surface Voids
Solid Agg.
Particle
Slide 76 Effective Specific Gravity
Gse is an aggregate property
Gse =
100 – Pb
100 – Pb
Gmm Gb
Slide 77
Voids in Mineral Aggregate
VMA is an indication of film thickness on
the surface of the aggregate
VMA = 100 –
Gmb Ps
Gsb
Slide 78
Volumetric Abbreviations
• Va – Air voids
• VMA – Voids Mineral Aggregate
• Pbe – Effective Asphalt Content
• VFA – Voids filled with Asphalt
• Vba – Volume of absorbed asphalt
78
Slide 79
Volumetric Terms
Continued
• Gsb – Bulk Specific Gravity of Stone
• Gse – Effective Specific Gravity of Stone
• Gb – Bulk Specific Gravity of Asphalt
• Gmb – Bulk Specific Gravity of Mix
• Gmm – Theoretical Maximum Specific
Gravity of Mixture
79
Slide 80
Gmb = 2.329
air
asphalt
Gb = 1.015
Pb = 5% by mix
aggregate
Gsb = 2.705
Gse = 2.731
absorbed asph
VOL (cm3 ) MASS (g)
1.000
Volumetric Properties – Phase Diagrams
Slide 81
air
asphalt
Gb = 1.015
aggregate
Gsb = 2.705
Gse = 2.731
absorbed asph
2.3291.000
0
0.108
0.008
0.116
2.213
0.182
VOL (cm3 ) MASS (g)
0.818
0.076
0.106
0.114
0.810
0.008
Air Voids = 7.6% Effective Asphalt Content = 4.6%
VMA = 18.2 % Absorbed Asphalt Content = 0.4%
VFA = 58.2 % Max Theo Sp Grav = 2.521
Slide 82
Chapter 5: Aggregates
Slide 83
HMA Mix Design
Marshall
Hveem
Superpave
83
Slide 84
Marshall Mix Design
• Uses impact hammer to prepare specimens
• Determine stability with Marshall stabilometer
• Uses volumetrics to select optimum asphalt content
84
Slide 85 Marshall Design Method
• Advantages
– Attention on voids, strength, durability
– Inexpensive equipment
– Easy to use in process control/acceptance
• Disadvantages
– Impact method of compaction
– Does not consider shear strength
– Load perpendicular to compaction axis
85
.
Slide 86
Hveem Mix Design
• Use kneading compactor to prepare specimens
• Determine stability with Hveem stabilometer
• Visual observation, volumetrics, and stability used to select
optimum asphalt content
86
Slide 87 Hveem Mix Design Method
87
Step 1
Design Series
Step 2
Flushing
Step 3
Min. Stability
Step 4
Max. AC with 4% Voids
The following steps are followed in
determining the design asphalt content:
• Step 1 – Record the four asphalt
contents used for preparing the mix
specimens. Record them in order of
increasing amount from left to right.
• Step 2 – Select from Step 1 the
three highest asphalt contents that do
not exhibit moderate or heavy flushing
and record them in step 2.
• Step 3 – Select from Step 2 the
two specimens that provide the
specified minimum stability and enter
them in step 3.
• Step 4 – Select from Step 3 the
highest asphalt content that provides at
least 4% air voids.
Slide 88 Hveem Mix Design
• Advantages
– Attention to voids, strength, durability
– Kneading compaction similar to field
– Strength parameter direct indication of internal friction component
of shear strength
• Disadvantages
– Equipment expensive and not easily portable
– Not wide range in stability measurements
88
Slide 89
Superpave Mix Design
• Uses gyratory compactor to prepare specimens
• Uses volumetric analysis to select optimum asphalt content
89
Slide 90
Superpave Gyratory Compactor
• Basis
– Corps of Engineers
– Texas equipment
– French / Australian operational
characteristics
• 150 mm diameter
– up to 37.5 mm nominal size
• Height Recorded
90
?
?
?
Slide 91
91
% binder
VMA
% binder
VFA
% binder
%Gmm at Nini
% binder
%Gmm at N
max
% binder
DP
% binder
Va
Blend 3
Selection of Design Asphalt
Binder Content
Slide 92
92
4 Steps of Superpave Mix Design
1. Materials Selection 2. Design Aggregate Structure
3. Design Binder Content 4. Moisture Sensitivity
TSR
Slide 93 a) Aggregate Selection
–depending on traffic level and how deep under surface
–coarse agg. angularity — min. % crushed particles
–fine agg. angularity — measured by unpacked air voids
(min.)
–Flat & elongated particles — max.
–Clay content — need small amount for bonding
–Gradation — 0.45 power chart
• curve must pass through control points
Slide 94
b) Binder Selection
based on service temps. as discussed earlier
Course Fine
Aggregate Aggregate Flat and Sand
Angularity Angularity Elongated Equivalency
Design Level (% min) (% min) (% max) (% min)
Light Traffic 55/- — — 40
Med. Traffic 75/- 40 10 40
Heavy Traffic 85/80 45 10 45
Superpave Consensus Aggregate Properties
Slide 95
c) Design Aggregate Structure
• prepare trial specimens with different aggregate
gradations & asphalt contents using the gyratory
compactor
• No. of gyrations is based on design high temp. &
traffic volume
• Design criteria:
–Nini < 89% Gmm –Ndes = 96% Gmm –Nmax < 98% Gmm
Slide 96
0.3
30
N
ini
N
des
N
max
Traffic Level (106 ESAL)
<0.3 0.3 - 3 3 - 30 >30
Nini 6 7 8 9
Ndes 50 75 100 125
Nmax 75 115 160 205
Number of Gyrations at Specific Design Traffic
Levels
Slide 97
Chapter 9: Asphalt
Slide 98 Moisture Susceptibility
• Stripping is loss of bond between asphalt & agg.
– several methods differing by specimen preparation, conditioning,
and strength requirements
– 2 sets of specimens: control & conditioned
– evaluate strength before and after conditioning
– Retained strength = conditioned strength / reference strength
– must have min. retained strength
Slide 99
Chapter 5: Aggregates
Slide 100
How to Improve Moisture Susceptibility
–Increase asphalt content
–Higher viscosity asphalt
–Clean aggregate of dust and clay
–Change aggregate gradation
–Add anti-stripping additives
• liquid
• portland cement or lime
Highway Mate
r
ials,
and Quality
CEE 483
• $ 1.5 trillion or ~ 17% of GDP
• ~ 12 % of U.S. Employment
• 50 miles per day per person
• Miles of Roadway:
• Interstate: 46,000+
• National Hwy System: 66,500
• All Other Paved: 2,282,000
• Unpaved: 1,479,000
• Annual investment: $18 + billion
• Pavement roughness increases vehicle
component failures.
• Bad roads cost motorists $$ billions
annually in repair and operating costs.
• Trucks use 4.5% less fuel on smooth
pavements than on rough.
Other Important Facts on
Pavements
• $15 Billion
• 500 million tons of
HMA
• 30 million tons of
liquid binder
Design
Struct Geom
PAVEMENTS
Construction
Materials
ManagementEvaluation
Traffic
Transportation Systems
CEE 483 / 583
CEE 514, 515
CEE 513
412/511 – 475
CEE 474
CEE 512
-CEE 372
ε
t
εc
εt
εc
εt at surface + bottom of all bound layers (cracking)
εc at midthickness of all layers + top of subgrade (rutting)
Subgrade
Soil
Base/
Subbase
Surface
SUR
εSUB
δSUR
Axle
Load
ε
Construction
NDT Load
“Strong”
Pavement “Weak”
Pavement
∆
NDT Sensors
NDT Load
∆
r
Functional
Performance
• Review of Basics
– Pavements types
– Factors affecting performance
– Distress and causes
• HMA
– with unbound (granular) base
– with bound (stabilized) base
– full-depth HMA
• Composite
– HMA over PCC
Wearing Course
Binder Course
Base Course (Bound or Unbound)
Subbase Course (Usually Unbound)
HMA
Surface
Subgrade Soil
• Structure:
What is the Role of Each
Pavement Layer ?
HMA Layer
Base Course
Subbase Course
Subgrade Soil
4 Roles:
Structural capacity
Frictional resistance
Smooth ride
Moisture barrier
Structural capacity
Keep Moisture from beneath
Structural capacity
Functional / Structural
Performance
Performance
Indicator Functional Structural
Distress √ √
Structural
Response √
Surface
Friction √
Roughness √
Traffic
Subgrade
Soil
Materials C&M
Variation
Environment
M&R
PAVEMENT
PERFORMANCE
Factors Affecting Pavement
Performance
M&R
Time (Years)
Preventive
Maint.
Routine
Maint.
Defer
Action Resurfacing
Reconstruction
Pavement
Condition
Good
Poor
Subgrade Soil
Subbase
Base
HMA Surface
Wheel
Load
Mechanism
Rutting
Wheel
Load
Mechanism
Fatigue Cracking
Location Along HMA Surface
Contraction
HMA
Friction on Underside of HMA Surface
Tensile
Stress
Crack or
Cold Joint
Crack or
Cold Joint
Surface
Tensile Strength
200+ mm
HMA
Surface
Oxidation Penetration
Surface-Initiated Crack
Interface Between Lifts
Separation
of asphalt
binder from
aggregate
Subbase Course
HMA Overlay
Subgrade Soil
PCC Slab Underlying Joint
Tension
Shear
Wheel
Load
Distress
Type
Traffic/
Load
Climate/
Materials
Fatigue Cracking
Block Cracking
Trans/Long Cracking
Potholes
Patch/Patch Deter.
Rutting/Shoving
Bleeding
Weathering/Raveling
LTPP Distress Identification
Manual
• Research-oriented
• All pavement types
• Distress definitions
• Schematic drawings
• Photographs
• Data collection
forms
HMA Mixtures
Plant Operations
Surface Preparation
Mix Delivery
HMA Placement
Joint Construction
Compaction
QC/QA
Troubleshooting
- Slide Number 1
- Slide Number 4
- Slide Number 5
- Slide Number 6
- Slide Number 7
- Other Important Facts on Pavements
- Slide Number 10
- Slide Number 14
- Functional Performance
- What is the Role of Each Pavement Layer ?
- Functional / Structural Performance
- Factors Affecting Pavement Performance
- Rutting Mechanism
- Slide Number 26
- Slide Number 28
- Fatigue Cracking Mechanism
- Slide Number 35
- Slide Number 37
- Slide Number 40
- LTPP Distress Identification Manual
Importance of Transportation
Importance of Pavements
Annual HMA Investment
Mix Design
Structural Design
Construction
Gross Loads
HMA Pavements
Types of HMA Pavements
Hot Mix Asphalt HMA
Pavement Performance
Problems / Distresses
Rutting
Fatigue Cracking
Thermal Cracking Mechanism
Transverse Cracking
Top-Down Cracking Mechanism
Stripping Mechanism
Reflection Crack Mechanism
Potholes
Block Cracking
Raveling
Bleeding
Common HMA Distresses
Schedule – Part 1: HMA
1
HMAMix Type
Selection
2
Conventional /
Dense-Gradation
3GAP-GRADED
4
OPEN-GRADED
5
Highway Noise
6
Highway Safety
• Increase highway safety measures by increasing driver visibility,
reducing standing surface water, and improving skid resistance.
7
8
9
10
11
12
HMA MATERIALS
Background
• First US hot mix asphalt
(HMA) constructed in
1870’s
– Pennsylvania Ave.
– Used naturally occurring
asphalt from surface of
lake on Island of Trinidad
• Two sources
– Island of Trinidad
– Bermudez, Venezuela
14
15
16
Petroleum-Based Asphalts
• Asphalt is waste product from refinery
processing of crude oil
– Sometimes called the “bottom of the barrel”
• Properties depend on:
– Refinery operations
– crude source
Gasoline
Kerosene
Lt. Gas Oil
Diesel
Motor Oils
Asphalt
Barrel of Crude Oil
17
Asphalt Cement Components
• Asphaltenes
– Large, discrete solid inclusions (black)
– High viscosity component
• Resins
– Semi-solid or solid at room temperature
• Fluid when heated
• Brittle when cold
• Oils
– Colorless liquid
– Soluble in most solvents
– Allows asphalt to flow
18
Refinery Operation
FIELD
STORAGE
PUMPING
STATION
LIGHT DISTILLATE
HEAVY DISTILLATE
PROCESS
UNIT
ASPHALT
CEMENTS
FOR PROCESSING INTO
EMULSIFIED AND
CUTBACK ASPHALTS
STILL
AIR
AIR
BLOWN
ASPHALT
STORAGE
TOWER
DISTILLATION
REFINERY
RESIDUUM
OR
GAS
PETROLEUM
SAND AND WATER
CONDENSERS
AND
COOLERS
TUBE
HEATER
MEDIUM DISTILLATE
19
Types
• Asphalt cements
• Cutbacks
• Emulsions
Early Specifications
• Lake Asphalts
– Appearance
– Solubility in carbon disulfide
• Petroleum asphalts (early 1900’s)
– Consistency
• Chewing
• Penetration machine
– Measure consistency
21
• Conventional Tests
Superpave /
SHRP Tests
Penetration AASHTO T49-93
Softening Point AASHTO T53-92
Rotational Viscosity AASHTO TP48
Dynamic Shear
Rheometer (DSR):
AASHTO PP1
Bending Beam
Rheometer
(BBR): AASHTO TP1-98
Binder Tests
Penetration
Testing
• Sewing machine needle
• Specified load, time, temperature
100 g
Initial
Penetration in 0.1 mm
After 5 seconds
23
Penetration Grades
40-50, 60-70, 85-
100
120-150, 200-300
# – #
Maximum penetration
Minimum penetration
24
Viscosity Graded
Specifications
25
AC Grades
AC-2.5, AC-5, AC-
10
AC-20, AC-30, AC-
40
AC- # 1/100 of midpoint of the
allowable viscosity
range.
AC-20, viscosity range
1,600 to 2,400 poises.
Asphalt cement
26
AR Grades
AR-10, AR-20, AR-40
AR-80, AR-160
AR- # 1/100 of midpoint of
viscosity after aging.
AR-40, viscosity range
3,000 to 5,000 poises.
Aged residue
27
RTFO
Flash Point
• Safety test
• Minimum temperature
with sufficient vapors
to “flash” when
exposed to flame
29
Solubility (Purity)
Testing
Absolute viscosity
– U-shaped tube with
timing marks & filled with
asphalt
– Placed in 60C bath
– Vacuum used to pull
asphalt through tube
– Time to pass marks
– Viscosity in Pa s (Poise)
Measures viscosity
• Ability to pump
binder at asphalt
plant
• Establish
temperature versus
viscosity relationship
Rotational Viscometer
32
Rotational Viscometer
spindle
torque
sample
sample
chamber
33
Temperature Susceptibility
Viscosity
Temperature
Too brittle (Thermal cracking)
Too soft (Rutting)
Optimum range
Of viscosity
34
Viscosity-Temperature Relationship
Viscosity – Temperature Relationship (Original Binder)
ARAC PG 58-28: y = -2.4795x + 7.6903
R2 = 0.989
0.0
0
.2
0.4
0.6
0.8
1.0
1.2
1.4
2.70 2.75 2.80 2.85 2.90 2.95
Log (Temp, oRankine)
L
og
(L
og
v
is
co
si
ty
, c
P
)
(41) (103) (171) (248) (335) (432)(deg F)
Pen
59, 77oF
Soft. Point
139oF
Brookfield Viscosity
200-350oF
35
.1
.2
.3
.5
1
10
5
100 110 120 130 140 150 160 170 180 190 200
Temperature,
C
Viscosity, Pa s
Compaction Range
Mixing Range
Mixing/Compaction
Temps
40
50
60
70
85
100
120
150
200
300
Penetration Grades
AC 40
AC 20
AC 10
AC 5
AC 2.5
100
50
10
5
V
is
co
si
ty
, 6
0C
(1
40
F)
AR 16000
AR 8000
AR 4000
AR 2000
AR 1000
General Comparison
37
New Superpave Binder
Specifications
Intended to improve pavement
performance by reducing the potential to:
Permanent deformation
Fatigue cracking
Low-temperature cracking
Excessive aging from volatilization
Pumping and handling
Test Equipment Performance Property
Rotational
Viscometer
Dynamic
Shear
Rheometer
Bending Beam
Rheometer
Direct
Tension
Tester
Handling
Pumping
Permanent
Deformation
Fatigue
Cracking
Thermal
Cracking
Flow
Rutting
Structural
Cracking
Low Temp.
Cracking
Chapter 9: Asphalt
Dynamic Shear
Rheometer
– Tests complex shear
modulus of binders
– measures the
resistance to shear
deformation in the
linear visco-elastic
range
height (h)
radius (r)
torque (T)
deflection angle (Θ)
40
Dynamic Shear Rheometer
Applied Stress
Fixed Plate
Asphalt
Oscillating
Plate
B C
A
Position of
Oscillating Plate
A
B
A
C
A
Time
1 cycle
41
Elastic Viscous
TimeA
A
B
C
Strain
Strain in-phase
δ = 0o
Strain out-of-phase
δ = 90o
42
Viscous Modulus, G”
Storage Modulus, G’
Complex Modulus, G*
δ
Complex Modulus is the vector sum of the
storage and viscous modulus
– Tests low temperature stiffness properties of
binders
– Measures midpoint deflection of a simply
supported beam
Bending Beam Rheometer
44
Bending Beam Rheometer
• S(t) = P L3
4 b h3 δ (t)
Where:
S(t) = creep stiffness (M Pa) at time, t
P = applied constant load, N
L = distance between beam supports (102 mm)
b = beam width, 12.5 mm
h = beam thickness, 6.25 mm
d(t) = deflection (mm) at time, t
Direct
Tension
• thermal
cracking
properties
46
εf
stress
strain
σf
Direct Tension Tester
L
Load
L+ ∆ L
∆L
failure strain (εf ) =
∆
effective length (L )
change in length ( L)
eL
e
47
Summary
Fatigue
CrackingRutting
RTFO
Short Term AgingNo aging
Construction
[RV] [DSR]
Low Temp
Cracking
[BBR]
[DTT]
PAV
Long Term Aging
48
PAV Components
Bottom of
pressure
aging
vessel
Rack of individual
pans
(50g of asphalt /
pan)
Vessel Lid Components
49
PG 46 PG 52 PG 58 PG 64 PG 70 PG 76 PG 82
(Rotational Viscosity) RV
90 90 100 100 100 (110) 100 (110) 110 (110)
(Flash Point) FP
46 52 58 64 70 76 82
46 52 58 64 70 76 82
(ROLLING THIN FILM OVEN) (ROLLING THIN FILM OVEN) RTFO RTFO Mass Loss Mass Loss << 1.00 % 1.00 %
(Direct Tension) DT
(Bending Beam Rheometer) BBR Physical Hardening
28
-34 -40 -46 -10 -16 -22 -28 -34 -40 -46 -16 -22 -28 -34 -40 -10 -16 -22 -28 -34 -40 -10 -16 -22 -28 -34 -40 -10 -16 -22 -28 -34 -10 -16 -22 -28 -34
Avg 7-day Max, oC
1-day Min, oC
(PRESSURE AGING VESSEL) (PRESSURE AGING VESSEL) PAVPAV
ORIGINALORIGINAL
< 5000 kPa
> 2.20 kPa
S < 300 MPa m > 0.300
Report Value
> 1.00 %
20 Hours, 2.07 MPa
10 7 4 25 22 19 16 13 10 7 25 22 19 16 13 31 28 25 22 19 16 34 31 28 25 22 19 37 34 31 28 25 40 37 34 31
(Dynamic Shear Rheometer) DSR G* sin δ
( Bending Beam Rheometer) BBR “S” Stiffness & “m”- value
-24 -30 -36 0 -6 -12 -18 -24 -30 -36 -6 -12 -18 -24 -30 0 -6 -12 -18 -24 -30 0 -6 -12 -18 -24 -30 0 -6 -12 -18 -24 0 -6 -12 -18 -24
-24 -30 -36 0 -6 -12 -18 -24 -30 -36 -6 -12 -18 -24 -30 0 -6 -12 -18 -24 -30 0 -6 -12 -18 -24 -30 0 -6 -12 -18 -24 0 -6 -12 -18 -24
(Dynamic Shear Rheometer) DSR G*/sin δ
(Dynamic Shear Rheometer) DSR G*/sin δ
< 3 Pa.s @ 135 oC
> 230 oC
CEC RWM
58 64
Test Temperature
Changes
Spec Requirement
Remains Constant
> 1.00 kPa
50
Superpave Asphalt Binders
• Grading System and Selection Based
Primarily on Climate
PG 58-22
Performance
Grade
Average 7-day
max pavement
design temp
Min pavement
design temp
6 degree increments
52
Aggregates
53
* Natural sands and gravels
– Underwater sources
+ Rivers & lakes
Barge-mounted dredges, draglines,
scoop, conveyors, or pumps
+ Relatively clean
– Land sources
+ Gravel or sand pits
Bucket loader
Excavation
54
Sizing
Stockpiling
Aggregate Properties
• Shape and texture
• Soundness
• Toughness
• Absorption
• Specific gravity
• Strength and modulus
• Gradation
• Deleterious materials and
cleanness
• Alkaline reactivity
• Affinity for asphalt
Chapter 5: Aggregates
angular rounded flaky
elongated flaky & elongated
http://pavementinteractive.org/index.php?title=Image:Flat_elongated
http://pavementinteractive.org/index.php?title=Image:Flat_elongated
Coarse Aggregates Particle
Shape & Surface Texture
Evaluation
• Texture and angularity –
Fractured faces
visual inspection to determine the percent of
aggregates with:
• no fractured faces
• % one fractured face
• % more than one fractured face
58
Common Aggregate
Properties
Toughness
Soundness
Deleterious Materials
Gradation
59
LA Abrasion Test
– Approx. 10% loss for extremely hard igneous rocks
– Approx. 60% loss for soft limestones and sandstones
Rotate for 500 revolutions at 30 to 33 rpm’s
60
Soundness
* Estimates resistance to weathering .
* Simulates freeze/thaw action by successively wetting
and drying aggregate in sodium sulfate or magnesium
sulfate solution
+ One immersion and drying is considered one
cycle
* Result is total percent loss over various sieve intervals
for a prescribed number of cycles
+ Max. loss values typically range from
10 to 20%per 5 cycles
61
Soundness
Before After
62 Aggregates
Clay Content (ASTM D2419)
• Percentage of clay in material finer than 4.75
mm sieve ASTM D2419 or AASHTO T 176
– Sand equivalent test method
Sedimented Agg.
Flocculating
Solution
Suspended Clay Clay Reading
Sand
Reading
SE = Sand Reading
Clay Reading *100
Chapter 5: Aggregates
64
• Aggregate Gradation
– The distribution of particle sizes expressed as
a percent of total weight.
– Determined by sieve analysis
Gradations
65
Gradations – Computation
Sieve Mass Cumulative
Retained Mass Retained % Retained % Passing
9.5
4.75
2.36
1.18
0.60
0.30
0.15
0.075
Pan
0.0
6.5
127.4
103.4
72.8
64.2
60.0
83.0
22.4
0.0
6.5
133.9
237.3
310.1
374.3
434.3
517.3
539.7
0.0
1.2
24.8
44.0
57.5
69.4
80.5
95.8
100.0
100.0
98.9
75.2
56.0
42.6
30.6
19.5
4.2
0.0
66
Aggregate Size Definitions
• Nominal Maximum Aggregate
Size
– one size larger than the first sieve
to retain more than 10%
• Maximum Aggregate Size
– one size larger than nominal
maximum size
100
100
90
72
65
48
36
22
15
9
4
100
99
89
72
65
48
36
22
15
9
4
Chapter 5: Aggregates
Chapter 5: Aggregates
Types of Gradation
69
Hot Mix Asphalt Concrete
(HMA)
Mix Designs
• Objective:
– Develop an economical blend of aggregates
and asphalt that meet design requirements
• Historical mix design methods
– Marshall
– Hveem
• New
– Superpave gyratory
70
Requirements in Common
• Sufficient asphalt to ensure a durable pavement
• Sufficient stability under traffic loads
• Sufficient air voids
– Upper limit to prevent excessive environmental
damage
– Lower limit to allow room for initial densification due
to traffic
• Sufficient workability
HMA Volumetric Terms
• Bulk specific gravity (BSG) of compacted HMA
• Maximum specific gravity
• Air voids
• Effective specific gravity of aggregate
• Voids in mineral aggregate, VMA
• Voids filled with asphalt, VFA
BSG of Compacted HMA
• AC mixed with agg. and compacted into
sample
Mass agg. and AC
Vol. agg., AC, air voids
Gmb =
Maximum Specific Gravity
Loose (uncompacted) mixture
Mass agg. and AC
Vol. agg. and AC
Gmm =
Percent Air Voids
Calculated using both specific gravities
Gmb
Gmm
Air voids = ( 1 – ) 100
Mass agg + AC
Vol. agg, AC, Air Voids
Mass agg + AC
Vol. agg, AC
=
Vol. agg, AC
Vol. agg, AC, Air Voids
Effective volume = volume of solid aggregate particle +
volume of surface voids not filled with asphalt
Gse =
Mass, dry
Effective Specific Gravity
Effective Volume
Absorbed asphalt
Vol. of water-perm. voids
not filled with asphalt
Surface Voids
Solid Agg.
Particle
Effective Specific Gravity
Gse is an aggregate property
Gse =
100 – Pb
100 – Pb
Gmm Gb
Voids in Mineral Aggregate
VMA is an indication of film thickness on
the surface of the aggregate
VMA = 100 – Gmb Ps
Gsb
78
Volumetric Abbreviations
• Va – Air voids
• VMA – Voids Mineral Aggregate
• Pbe – Effective Asphalt Content
• VFA – Voids filled with Asphalt
• Vba – Volume of absorbed asphalt
79
Volumetric Terms
Continued
• Gsb – Bulk Specific Gravity of Stone
• Gse – Effective Specific Gravity of Stone
• Gb – Bulk Specific Gravity of Asphalt
• Gmb – Bulk Specific Gravity of Mix
• Gmm – Theoretical Maximum Specific
Gravity of Mixture
Gmb = 2.329
air
asphalt
Gb = 1.015
Pb = 5% by mix
aggregate
Gsb = 2.705
Gse = 2.731
absorbed asph
VOL (cm3 ) MASS (g)
1.000
Volumetric Properties – Phase Diagrams
air
asphalt
Gb = 1.015
aggregate
Gsb = 2.705
Gse = 2.731
absorbed asph
2.3291.000
0
0.108
0.008
0.116
2.213
0.182
VOL (cm3 ) MASS (g)
0.818
0.076
0.106
0.114
0.810
0.008
Air Voids = 7.6% Effective Asphalt Content = 4.6%
VMA = 18.2 % Absorbed Asphalt Content = 0.4%
VFA = 58.2 % Max Theo Sp Grav = 2.521
Chapter 5: Aggregates
83
HMA Mix Design
Marshall
Hveem
Superpave
84
Marshall Mix Design
• Uses impact hammer to prepare specimens
• Determine stability with Marshall stabilometer
• Uses volumetrics to select optimum asphalt
content
85
Marshall Design Method
• Advantages
– Attention on voids, strength, durability
– Inexpensive equipment
– Easy to use in process control/acceptance
• Disadvantages
– Impact method of compaction
– Does not consider shear strength
– Load perpendicular to compaction axis
86
• Use kneading compactor to prepare specimens
• Determine stability with Hveem stabilometer
• Visual observation, volumetrics, and stability used to
select optimum asphalt content
Hveem Mix Design
87
Hveem Mix Design Method
Step 1
Design Series
Step 2
Flushing
Step 3
Min. Stability
Step 4
Max. AC with 4% Voids
88
Hveem Mix Design
• Advantages
– Attention to voids, strength, durability
– Kneading compaction similar to field
– Strength parameter direct indication of internal
friction component of shear strength
• Disadvantages
– Equipment expensive and not easily portable
– Not wide range in stability measurements
89
Superpave Mix Design
• Uses gyratory compactor to prepare specimens
• Uses volumetric analysis to select optimum
asphalt content
90
• Basis
– Corps of Engineers
– Texas equipment
– French / Australian operational
characteristics
• 150 mm diameter
– up to 37.5 mm nominal size
• Height Recorded
?
?
?
Superpave Gyratory
Compactor
91
% binder
VMA
% binder
VFA
% binder
%Gmm at Nini
% binder
%Gmm at Nmax
% binder
DP
% binder
Va
Blend 3
Selection of Design Asphalt
Binder Content
92
4 Steps of Superpave Mix Design
1. Materials Selection 2. Design Aggregate Structure
3. Design Binder Content 4. Moisture Sensitivity
TSR
a) Aggregate Selection
– depending on traffic level and how deep
under surface
– coarse agg. angularity — min. % crushed
particles
– fine agg. angularity — measured by unpacked
air voids (min.)
– Flat & elongated particles — max.
– Clay content — need small amount for
bonding
– Gradation — 0.45 power chart
• curve must pass through control points
b) Binder Selection
based on service temps. as discussed earlier
Course Fine
Aggregate Aggregate Flat and Sand
Angularity Angularity Elongated Equivalency
Design Level (% min) (% min) (% max) (% min)
Light Traffic 55/- — — 40
Med. Traffic 75/- 40 10 40
Heavy Traffic 85/80 45 10 45
Superpave Consensus Aggregate Properties
• prepare trial specimens with different
aggregate gradations & asphalt contents
using the gyratory compactor
• No. of gyrations is based on design high
temp. & traffic volume
• Design criteria:
– Nini < 89% Gmm
– Ndes = 96% Gmm
– Nmax < 98% Gmm
c) Design Aggregate Structure
<0.3 >30 Nini Ndes Nmax
Traffic Level (106 ESAL)
<0.3 0.3 - 3 3 - 30 >30
Nini 6 7 8 9
Ndes 50 75 100 125
Nmax 75 115 160 205
Number of Gyrations at Specific Design Traffic
Levels
Chapter 9: Asphalt
• Stripping is loss of bond between asphalt & agg.
– several methods differing by specimen
preparation, conditioning, and strength
requirements
– 2 sets of specimens: control & conditioned
– evaluate strength before and after conditioning
– Retained strength = conditioned strength /
reference strength
– must have min. retained strength
Moisture Susceptibility
Chapter 5: Aggregates
How to Improve Moisture Susceptibility
– Increase asphalt content
– Higher viscosity asphalt
– Clean aggregate of dust and clay
– Change aggregate gradation
– Add anti-stripping additives
• liquid
• portland cement or lime
HMA Mix Type Selection
Slide Number 2
Slide Number 3
Slide Number 4
Highway Noise
Highway Safety
Slide Number 7
Slide Number 8
Slide Number 9
Slide Number 10
Slide Number 11
HMA MATERIALS�
Background
Slide Number 14
Slide Number 15
Petroleum-Based Asphalts
Asphalt Cement Components
Refinery Operation
Types
Early Specifications
Binder Tests
Penetration Testing
Penetration Grades
Viscosity Graded Specifications
AC Grades
AR Grades
RTFO
Flash Point
Solubility (Purity)
Testing
Rotational Viscometer
Rotational Viscometer
Temperature Susceptibility
Viscosity-Temperature Relationship
Mixing/Compaction Temps
General Comparison
New Superpave Binder Specifications
Slide Number 38
Dynamic Shear Rheometer
Dynamic Shear Rheometer
Slide Number 41
Slide Number 42
Bending Beam Rheometer
Bending Beam Rheometer
Direct Tension
Direct Tension Tester
Summary
Slide Number 48
Slide Number 49
Superpave Asphalt Binders
Slide Number 51
Aggregates
Excavation
Sizing
Aggregate Properties
Slide Number 56
Coarse Aggregates Particle Shape & Surface Texture Evaluation
Common Aggregate Properties
LA Abrasion Test
Slide Number 60
Soundness
Clay Content (ASTM D2419)
Slide Number 63
Gradations
Slide Number 65
Aggregate Size Definitions
Slide Number 67
Slide Number 68
Hot Mix Asphalt Concrete (HMA)�Mix Designs
Requirements in Common
HMA Volumetric Terms
BSG of Compacted HMA
Maximum Specific Gravity
Percent Air Voids
Effective Specific Gravity
Slide Number 76
Slide Number 77
Volumetric Abbreviations
Volumetric Terms�Continued
Slide Number 80
Slide Number 81
Slide Number 82
HMA Mix Design
Marshall Mix Design
Marshall Design Method
Hveem Mix Design
Hveem Mix Design Method
Hveem Mix Design
Superpave Mix Design
Superpave Gyratory Compactor
Slide Number 91
Slide Number 92
Slide Number 93
Slide Number 94
c) Design Aggregate Structure
Slide Number 96
Slide Number 97
Moisture Susceptibility
Slide Number 99
Slide Number 100
1
Hot Mix Asphalt (HMA)
Volumetric Properties
Using
Phase Diagrams
Gmb =
2.329
air
asphalt
Gb = 1.01
5
Pb = 5% by mix
aggregate
Gsb = 2.705
Gse = 2.731
absorbed asph
VOL (cm3 ) MASS (g)
1.000
2
Gmb = 2.329
air
asphalt
Gb = 1.015
Pb = 5% by mix
aggregate
Gsb = 2.705
Gse = 2.731
absorbed asph
VOL (cm3 ) MASS (g)
1.00
0
Ma = 0
Mm = 1.0 x 2.329 x 1.0 = 2.329
M = V x G x
1.000
Gmb = 2.329
air
asphalt
Gb = 1.015
Pb = 5% by mix
aggregate
Gsb = 2.705
Gse = 2.731
absorbed asph
VOL (cm3 ) MASS (g)
1.000
0
2.329
0.116 Mb = 0.05 x 2.329 =
Ms = 2.329 – 0.116 = 2.213
3
air
asphalt
Gb = 1.015
aggregate
Gsb = 2.705
Gse = 2.731
absorbed asph
2.329 1.000
0
0.11
6
2.213
VOL (cm3 ) MASS (g)
0.818
V =
M
G x 1.000
Vse = 2.213 =
0.810
2.731x 1.0
0.810
Vsb = 2.213 = 0.818
2.705x 1.0
air
asphalt
Gb = 1.015
aggregate
Gsb = 2.705
Gse = 2.731
absorbed asph
2.329 1.000
0
0.116
2.213
VOL (cm3 ) MASS (g)
0.818
0.11
4
0.810
0.008
V =
M
G x 1.000
Vb = 0.116 = 0.114
1.015 x 1.0
Vba = 0.818 – 0.810 = 0.008
4
air
asphalt
Gb = 1.015
aggregate
Gsb = 2.705
Gse = 2.731
absorbed asph
2.329 1.000
0
0.116
2.213
VOL (cm3 ) MASS (g)
0.818
0.076
0.106
0.114
0.810
0.008
Vbe = 0.114 – 0.008 = 0.106
Va = 1.000 – 0.114 – 0.810 = 0.076
air
asphalt
Gb = 1.015
aggregate
Gsb = 2.705
Gse = 2.731
absorbed asph
2.329 1.000
0
0.108
0.008
0.116
2.213
VOL (cm3 ) MASS (g)
0.818
0.076
0.106
0.114
0.810
0.008
M = V x G x 1.000 Mbe = 0.106 x 1.015 x 1.000 = 0.108
Mba = 0.116 – 0.108 = 0.008
5
air
asphalt
Gb = 1.015
aggregate
Gsb = 2.705
Gse = 2.731
absorbed asph
2.329 1.000
0
0.108
0.008
0.116
2.213
0.182
VOL (cm3 ) MASS (g)
0.818
0.076
0.106
0.114
0.810
0.008
VMA = Vbe + Va = ( 0.106 + 0.076 ) x 100 = 18.2 %
Air Voids = 0.076 x 100 = 7.6 %
air
asphalt
Gb = 1.015
aggregate
Gsb = 2.705
Gse = 2.731
absorbed asph
2.329 1.000
0
0.108
0.008
0.116
2.213
0.182
VOL (cm3 ) MASS (g)
0.818
0.076
0.106
0.114
0.810
0.008
Air Voids = 7.6 %
VMA = 18.2 %
VFA = ( 0.106 / 0.182 ) x 100 = 58.2 %
6
air
asphalt
Gb = 1.015
aggregate
Gsb = 2.705
Gse = 2.731
absorbed asph
2.329 1.000
0
0.108
0.008
0.116
2.213
0.182
VOL (cm3 ) MASS (g)
0.818
0.076
0.106
0.114
0.810
0.008
Air Voids = 7.6 % Eff. Asp. Cont. = ( 0.108 / 2.329 ) x 100 = 4.6 %
VMA = 18.2 %
VFA = 58.2 %
air
asphalt
Gb = 1.015
aggregate
Gsb = 2.705
Gse = 2.731
absorbed asph
2.329 1.000
0
0.108
0.008
0.116
2.213
0.182
VOL (cm3 ) MASS (g)
0.818
0.076
0.106
0.114
0.810
0.008
Air Voids = 7.6% Effective Asphalt Content = 4.6%
VMA = 18.2 % Abs. Asph. Cont. = ( 0.008 / 2.213 ) x 100 = 0.4%
VFA = 58.2 %
7
air
asphalt
Gb = 1.015
aggregate
Gsb = 2.705
Gse = 2.731
absorbed asph
2.329 1.000
0
0.108
0.008
0.116
2.213
0.182
VOL (cm3 ) MASS (g)
0.818
0.076
0.106
0.114
0.810
0.008
Air Voids = 7.6% Max Theo Sp Grav = 2.329 = 2.521
VMA = 18.2 %
VFA = 58.2 %
1.000 – 0.076
1.000
air
asphalt
Gb = 1.015
aggregate
Gsb = 2.705
Gse = 2.731
absorbed asph
2.329 1.000
0
0.108
0.008
0.116
2.213
0.182
VOL (cm3 ) MASS (g)
0.818
0.076
0.106
0.114
0.810
0.008
Air Voids = 7.6% Effective Asphalt Content = 4.6%
VMA = 18.2 % Absorbed Asphalt Content = 0.4%
VFA = 58.2 % Max Theo Sp Grav = 2.521